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Full-Text Articles in Engineering

Electroelastic Effect Of Thickness Mode Langasite Resonators, Haifeng Zhang, Joseph A. Turner, J. S. Yang, J. A. Kosinski Oct 2007

Electroelastic Effect Of Thickness Mode Langasite Resonators, Haifeng Zhang, Joseph A. Turner, J. S. Yang, J. A. Kosinski

Department of Engineering Mechanics: Faculty Publications

Langasite is a very promising material for resonators due to its good temperature behavior and high piezoelectric coupling, low acoustic loss, and high Q factor. The biasing effect for langasite resonators is crucial for resonator design. In this article, the resonant frequency shift of a thickness-mode langasite resonator is analyzed with respect to a direct current (DC) electric field applied in the thickness direction. The vibration modes of a thin langasite plate fully coated with an electrode are analyzed. The analysis is based on the theory for small fields superposed on a bias in electroelastic bodies and the first-order perturbation …


Adhesive Contact In Filaments, Xiang-Fa Wu, Yuris A. Dzenis Jun 2007

Adhesive Contact In Filaments, Xiang-Fa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

This paper studies the elastic contact in filaments induced by surface adhesion, which plays an important role in the mechanical response of fibrous materials (e.g., fiber friction, sliding, compression hysteresis, etc.). During the process, a simple 3D elastic contact model was proposed. The filaments were assumed to be uniform, smooth elastic cylinders, and the adhesive force between filaments in contact was estimated according to Bradley’s approach (Bradley 1932 Phil. Mag. 13 853) that relies on the filament configurations before deformation. Under the action of fiber surface adhesion, the elastic deformation and the size of the contact zone were determined in …


Collapse Analysis Of Nanofibers, Xiang-Fa Wu, Yuris A. Dzenis Jun 2007

Collapse Analysis Of Nanofibers, Xiang-Fa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Continuous nanofibers fabricated by the electrospinning technique have found increasing applications (e.g., nanofiber composites, nanofiber devices, bioengineering tissue scaffolding, etc.). For a nanofiber network subjected to a small external perturbation, the fiber segments within the network may deflect and stick to each other under the condition that their surface adhesion energy overcomes the elastic strain energy induced by fiber bending. Therefore, this paper aims to study adhesion-induced nanofiber collapse and relevant criteria. A simple fiber collapse model was proposed, which is based on the contact of two deflected elastic filaments under surface adhesion. Four fundamental fiber collapse modes (i.e., fiber-flat …


Calibration Of Atomic Force Microscope Cantilevers Using Piezolevers, Saltuk B. Aksu, Joseph A. Turner Apr 2007

Calibration Of Atomic Force Microscope Cantilevers Using Piezolevers, Saltuk B. Aksu, Joseph A. Turner

Department of Engineering Mechanics: Faculty Publications

The atomic force microscope (AFM) can provide qualitative information by numerous imaging modes, but it can also provide quantitative information when calibrated cantilevers are used. In this article a new technique is demonstrated to calibrate AFM cantilevers using a reference piezolever. Experiments are performed on 13 different commercially available cantilevers. The stiff cantilevers, whose stiffness is more than 0.4 N/m, are compared to the stiffness values measured using nanoindentation. The experimental data collected by the piezolever method is in good agreement with the nanoindentation data. Calibration with a piezolever is fast, easy, and nondestructive and a commercially available AFM is …


Computational Constitutive Model For Predicting Nonlinear Viscoelastic Damage And Fracture Failure Of Asphalt Concrete Mixtures, Yong-Rak Kim, D. H. Allen, D. N. Little Apr 2007

Computational Constitutive Model For Predicting Nonlinear Viscoelastic Damage And Fracture Failure Of Asphalt Concrete Mixtures, Yong-Rak Kim, D. H. Allen, D. N. Little

Department of Engineering Mechanics: Faculty Publications

A computational constitutive model was developed to predict damage and fracture failure of asphalt concrete mixtures. Complex heterogeneity and inelastic mechanical behavior are addressed by the model by using finite-element methods and elastic– viscoelastic constitutive relations. Damage evolution due to progressive cracking is represented by randomly oriented interface fracture, which is governed by a newly developed nonlinear viscoelastic cohesive zone model. Computational simulations demonstrate that damage evolution and failure of asphalt concrete mixtures is dependent on the mechanical properties of the mixture. This approach is suitable for the relative evaluation of asphalt concrete mixtures by simply employing material properties and …


Wrinkling Of A Charged Elastic Film On A Viscous Layer, Xiang-Fa Wu, Yuris A. Dzenis, Kyle W. Strabala Feb 2007

Wrinkling Of A Charged Elastic Film On A Viscous Layer, Xiang-Fa Wu, Yuris A. Dzenis, Kyle W. Strabala

Department of Engineering Mechanics: Faculty Publications

A thin metallic film deposited on a compliant polymeric substrate begins to wrinkle under compression induced in curing process and afterwards cooling of the system. The wrinkle mode depends upon the thin film elasticity, thickness, compressive strain, as well as mechanical properties of the compliant substrate. This paper presents a simple model to study the modulation of the wrinkle mode of thin metallic films bonded on viscous layers in external electric field. During the procedure, linear perturbation analysis was performed for determining the characteristic relation that governs the evolution of the plane-strain wrinkle of the thin films under varying conditions, …


A New Mass Sensor Based On Thickness-Twist Edge Modes In A Piezoelectric Plate, J.S. Yang, A. K. Soh Jan 2007

A New Mass Sensor Based On Thickness-Twist Edge Modes In A Piezoelectric Plate, J.S. Yang, A. K. Soh

Department of Engineering Mechanics: Faculty Publications

We propose a new mass sensor based on thickness-twist edge modes in a piezoelectric plate of 6mm crystals. By performing a theoretical analysis, a simple expression of sensitivity is obtained. The proposed sensor has an important advantage in the sense that it can be mounted away from the edge of the plate where the motion is insignificant and, thus, the operation of the device is unaffected.


Effect Of Interface Modification On The Mechanical Behavior Of Carbon Nanotube Reinforced Composites Using Parallelmolecular Dynamics Simulations, S. Namilae, U. Chandra, A. Srinivasan, Namas Chandra Jan 2007

Effect Of Interface Modification On The Mechanical Behavior Of Carbon Nanotube Reinforced Composites Using Parallelmolecular Dynamics Simulations, S. Namilae, U. Chandra, A. Srinivasan, Namas Chandra

Department of Engineering Mechanics: Faculty Publications

Molecular dynamics (MD) simulations play an important predictive role in understanding the behavior of nanoscale systems. In this paper, parallel MD simulations are used to understand the mechanical behavior of interfaces in CNT based composites. We present an algorithm for parallel implementation of MD simulations of carbon nanotube (CNT) based systems using reactive bond order potentials. We then use that algorithm to model the CNT-polymer interfaces with various levels of interaction as (a) described only by long range Van Der Waals interactions (b) chemically bonded with fixed matrix and (c) chemically bonded with matrix explicitly modeled. It is shown that …


Influence Of Van Der Waals Forces On Increasing The Strength And Toughness In Dynamic Fracture Of Nanofibre Networks: A Peridynamic Approach, Florin Bobaru Ph.D. Jan 2007

Influence Of Van Der Waals Forces On Increasing The Strength And Toughness In Dynamic Fracture Of Nanofibre Networks: A Peridynamic Approach, Florin Bobaru Ph.D.

Department of Engineering Mechanics: Faculty Publications

The peridynamic method is used here to analyse the effect of van der Waals forces on the mechanical behaviour and strength and toughness properties of three-dimensional nanofibre networks under imposed stretch deformation. The peridynamic formulation allows for a natural inclusion of long-range forces (such as van der Waals forces) by considering all interactions as ‘long-range’. We use van der Waals interactions only between different fibres and do not need to model individual atoms. Fracture is introduced at the microstructural (peridynamic bond) level for the microelastic type bonds, while van der Waals bonds can reform at any time. We conduct statistical …


Effects Of Middle Plane Curvature On Vibrations Of A Thickness-Shear Mode Crystal Resonator, J. S. Yang, Xiaomeng Yang, Joseph A. Turner, John A. Kosinski, Robert A. Pastore, Weiping Zhang Oct 2006

Effects Of Middle Plane Curvature On Vibrations Of A Thickness-Shear Mode Crystal Resonator, J. S. Yang, Xiaomeng Yang, Joseph A. Turner, John A. Kosinski, Robert A. Pastore, Weiping Zhang

Department of Engineering Mechanics: Faculty Publications

We study the effects of a small curvature of the middle plane of a thickness-shear mode crystal plate resonator on its vibration frequencies, modes and acceleration sensitivity. Two-dimensional equations for coupled thickness-shear, flexural and extensional vibrations of a shallow shell are used. The equations are simplified to a single equation for thickness-shear, and two equations for coupled thickness-shear and extension. Equations with different levels of coupling are used to study vibrations of rotated Y-cut quartz and langasite resonators. The influence of the middle plane curvature and coupling to extension is examined. The effect of middle plane curvature on normal acceleration …


Role Of Atomic Scale Interfaces In The Compressive Behavior Of Carbon Nanotubes In Composites, S. Namilae, Namas Chandra Oct 2006

Role Of Atomic Scale Interfaces In The Compressive Behavior Of Carbon Nanotubes In Composites, S. Namilae, Namas Chandra

Department of Engineering Mechanics: Faculty Publications

Carbon nanotubes (CNT) are potentially promising fibers for ultra high strength composites. In order to fully har-ness the outstanding mechanical properties of carbon nanotubes as fiber reinforcements, it is essential to understand the nature of load transfer between fiber and matrix under various types of loading conditions that include tension, compression, torsion and a combination thereof. In this paper, we study the compressive behavior (buckling and post-buckling) of carbon nanotubes in the neat form, when they are embedded in polyethylene matrix and with in¬terface chemical modifications using molecular dynamics simulations based on Tersoff–Brenner potential. It is ob¬served that the critical …


Droplet On A Fiber: Geometrical Shape And Contact Angle, Xiangfa Wu, Yuris A. Dzenis Jul 2006

Droplet On A Fiber: Geometrical Shape And Contact Angle, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

This paper is concerned with the geometrical shape, wetting length, and contact angle of a microdroplet on a fiber by using the method free energy variation. The governing equation and relevant boundary conditions of the microdroplet were re-derived based on the free energy variation of the droplet/ fiber system. The geometrical shape of the droplet was determined as the combination of Legendre’s elliptical functions of the first and second kinds, corresponding to the previous results in literature [6]. For contact angle h >15 degree, a novel efficient semi-analytic approach was proposed to extract the contact angle from experimental data. The …


Optimization Of Multilayer Wear-Resistant Thin Films Using Finite Element Analysis On Stiff And Compliant Substrates, R. K. Lakkaraju, Florin Bobaru, S. L. Rohde Jan 2006

Optimization Of Multilayer Wear-Resistant Thin Films Using Finite Element Analysis On Stiff And Compliant Substrates, R. K. Lakkaraju, Florin Bobaru, S. L. Rohde

Department of Engineering Mechanics: Faculty Publications

Extensive research has been carried out by researchers on the growth and characterization of multilayer protective coatings, but the design of these coatings still remains largely empirical. In this regard, recent progress has been made in developing a design approach for optimizing a multilayer coating structure before deposition, which would help save time and material. In pursuit of an optimal design, finite element analysis using a plane strain Hertzian contact model was developed to investigate the stress/ strain behavior within the layers of the system. The present study looks to find the optimal thicknesses of individual layers in a multilayer …


A Model For Predicting The Evolution Of Multiple Cracks On Multiple Length Scales In Viscoelastic Composites, David H. Allen, C. R. Searcy Jan 2006

A Model For Predicting The Evolution Of Multiple Cracks On Multiple Length Scales In Viscoelastic Composites, David H. Allen, C. R. Searcy

Department of Engineering Mechanics: Faculty Publications

A model is presented herein for predicting the evolution of numerous cracks on multiple length scales, the objective of such a model being to develop the capability to predict failure of structural components to perform their intended tasks. Such a capability would then be useful as a predictive tool for designing structural components so as not to fail, but rather to succeed in performing their intended tasks. The model developed herein is somewhat involved, being based in continuum mechanics and thermodynamics, but is nevertheless expected to be cost effective (wherever sufficient accuracy permits) when compared to more costly experimental means …


E(Fg)2: A New Fixed-Grid Shape Optimization Method, Florin Bobaru Ph.D., Srinivas Rachakonda Jan 2006

E(Fg)2: A New Fixed-Grid Shape Optimization Method, Florin Bobaru Ph.D., Srinivas Rachakonda

Department of Engineering Mechanics: Faculty Publications

We propose a shape optimization method over a fixed grid. Nodes at the intersection with the fixed grid lines track the domain’s boundary. These “floating” boundary nodes are the only ones that can move/appear/disappear in the optimization process. The element-free Galerkin (EFG) method, used for the analysis problem, provides a simple way to create these nodes. The fixed grid (FG) defines integration cells for EFG method. We project the physical domain onto the FG and numerical integration is performed over partially cut cells. The integration procedure converges quadratically. The performance of the method is shown with examples from shape optimization …


Elasticity Of Planar Fiber Networks, Xiangfa Wu, Yuris A. Dzenis Nov 2005

Elasticity Of Planar Fiber Networks, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

A micromechanics model is proposed for the elasticity of planar fiber networks (FNs). The FN is created by random deposition of linearly elastic straight rods within a region. The rods are bonded rigidly at contacts. Under external in-plane loading, the FN deformation consists of fiber bending, elongation, and contraction. An effective constitutive relation for fiber network is developed by averaging the strain energy dissipated by all possible fiber deformations in all directions. Numerical calculations are performed to analyze the effects of fiber aspect ratio and fiber concentration on the effective stiffness of the planar random FN. Finite element analysis (FEA) …


Damage-Induced Modeling Of Asphalt Mixtures Through Computational Micromechanics And Cohesive Zone Fracture, Yong-Rak Kim, D. H. Allen, D. N. Little Oct 2005

Damage-Induced Modeling Of Asphalt Mixtures Through Computational Micromechanics And Cohesive Zone Fracture, Yong-Rak Kim, D. H. Allen, D. N. Little

Department of Engineering Mechanics: Faculty Publications

This paper presents a computational micromechanics modeling approach to predict damage-induced mechanical response of asphalt mixtures. Heterogeneous geometric characteristics and inelastic mechanical behavior were taken into account by introducing finite element modeling techniques and a viscoelastic material model. The modeling also includes interface fracture to represent crack growth and damage evolution. The interface fracture is modeled by using a micromechanical nonlinear viscoelastic cohesive-zone constitutive relation. Fundamental material properties and fracture characteristics were measured from simple laboratory tests and then incorporated into the model to predict rate-dependent viscoelastic damage behavior of the asphalt mixture. Simulation results demonstrate that each model parameter …


Antiplane Surface Acoustic Waves Propagating In Elastic Half-Space Coated With An Anisotropic Laminate, Xiangfa Wu, Yuris A. Dzenis Sep 2005

Antiplane Surface Acoustic Waves Propagating In Elastic Half-Space Coated With An Anisotropic Laminate, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Dispersion relation of antiplane surface acoustic waves (SAWs) propagating in elastic half-space coated with an anisotropic laminate was determined explicitly by means of Stroh's formalism within the subsonic range, where is no energy leakage into the substrate. During the procedure, the governing dynamic equation in each anisotropic layer and the displacement–traction continuity at interfaces were exactly satisfied by Stroh's functions. Explicit algebraic equation was derived for determining the dispersion relation. As an example, the wave number vs. phase velocity diagram for steel half-space coated with a graphite-fiber/epoxy laminate with a [± 45°/0°2] lay-up was demonstrated. The given method …


Electrohydrodynamic Instability Of Thin Conductive Liquid Films, Xiangfa Wu, Yuris A. Dzenis Aug 2005

Electrohydrodynamic Instability Of Thin Conductive Liquid Films, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

This paper considers the effect of surface charges on the surface instability of thin conductive liquid films. A characteristic relation is obtained for determining the wave number of the fastest growing mode as a function of surface tension, dispersive van der Waals force, and electrostatic tractions exerted by the film surface charges. Two natural length scales of the microsystem are further introduced to account for the coupling effects on the dewetting pattern development. The present results can be used for controlled surface pattern modulation in a spinodal-dewetting scenario via amplification of surface waves of selected modes.


Experimental Determination Of Probabilistic Edge-Delamination Strength Of A Graphite–Fiber/Epoxy Composite, Xiangfa Wu, Yuris A. Dzenis Aug 2005

Experimental Determination Of Probabilistic Edge-Delamination Strength Of A Graphite–Fiber/Epoxy Composite, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Probabilistic edge-delamination strength of a thermosetting polymer composite was studied experimentally in this work. During the procedure, by means of edge-delamination tensile test, the graphite–fiber/epoxy laminate made of unidirectional Toray P7051S- 20Q-1000 prepregs with an optimized lay-up of [122/–122/02]S was used for examining its probabilistic distributions of the edgedelamination onset stress and the ultimate tensile strength. Acoustic emission (AE) equipment and optical microscope were utilized to capture the edge-delamination initiation and characterize the failure modes during delaminating. Fractographical analysis based on scanning electron microscope (SEM) was conducted for the characterization of the microscopic …


Determination Of Dynamic Delamination Toughness Of A Graphite-Fiber/Epoxy Composite Using Hopkinson Pressure Bar, Xiangfa Wu, Yuris A. Dzenis May 2005

Determination Of Dynamic Delamination Toughness Of A Graphite-Fiber/Epoxy Composite Using Hopkinson Pressure Bar, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Modified dynamic three-point-bending and compact shearing test configurations based on Hopkinson pressure bar (HPB) and crack detection gage (CDG) (Vishay Intertechnology, Inc) were used for the determination of the dynamic mode I and mode II delamination-initiation toughness of a unidirectional graphite-fiber/epoxy composite made of P7051S-20Q-1000 prepregs (Toray Composites America). The transient loading history was recorded precisely by the HPB installed with a highresolution digital oscilloscope, and the crack initiation and delay time were captured using the CDG. By means of dynamic finite-element analysis (FEA) of the impact processes with the loading history and crack initiation time as input, the critical …


Colossal Dielectric And Electromechanical Responses In Self Assembled Polymeric Nanocomposites, Cheng Huang, Q. M. Zhang, Jiang Yu Li, Manese Rabeony Jan 2005

Colossal Dielectric And Electromechanical Responses In Self Assembled Polymeric Nanocomposites, Cheng Huang, Q. M. Zhang, Jiang Yu Li, Manese Rabeony

Department of Engineering Mechanics: Faculty Publications

An electroactive polymer nanocomposite, in which high dielectric constant copper phthalocyanine oligomer (o-CuPc) nanoparticles are incorporated into the block polyurethane (PU) matrix by the combination of “top down” and “bottom up” approaches, was realized. Such an approach enables the nanocomposite to exhibit colossal dielectric and electromechanical responses with very low volume fraction of the high dielectric constant o-CuPc nanofillers (~3.5%) in the composite. In contrast, a simple blend of o-CuPc and PU composite with much higher o-CuPc content (~16% of o-CuPc) shows much lower dielectric and electromechanical responses.


A Model For Predicting The Evolution Of Damage In Viscoelastic Particle-Reinforced Composites, G. D. Seidel, D. H. Allen, K. L. E. Helms, S. E. Groves Jan 2005

A Model For Predicting The Evolution Of Damage In Viscoelastic Particle-Reinforced Composites, G. D. Seidel, D. H. Allen, K. L. E. Helms, S. E. Groves

Department of Engineering Mechanics: Faculty Publications

A viscoelastic cohesive zone model is employed within the framework of a finite element code to analyze a two-phase viscoelastic particle-reinforced composite material consisting of a relatively stiff aggregate embedded in a copolymer binder. The composite of interest, LX17, is noted to have a very large aggregate volume fraction and as such, aggregate grain boundaries were generated within finite element meshes along which viscoelastic cohesive zones have been embedded to model the binder. It has been observed experimentally that the majority of damage in LX17 occurs within the binder, and thus, a damage evolution law has been applied to the …


Edge-Cracked Orthotropic Bimaterial Butt Joint Under Antiplane Singularity, Xiangfa Wu, Yuris A. Dzenis, Emrah Gokdag Nov 2004

Edge-Cracked Orthotropic Bimaterial Butt Joint Under Antiplane Singularity, Xiangfa Wu, Yuris A. Dzenis, Emrah Gokdag

Department of Engineering Mechanics: Faculty Publications

Explicit elastic solutions are given for an edge-cracked orthotropic bimaterial butt joint under antiplane singularity of a screw dislocation and a line-force. During the procedure, conformal mapping and known dislocation solution are utilized for constructing the fundamental solution to the present problem. Stress intensity factor (SIF) and energy release rate (ERR) of the edge-cracked butt joint are given in closed-form. In limiting cases, results provided in this work cover those in literature.


Screw Dislocation Interacting With Interfacial Edge-Cracks In Piezoelectric Bimaterial Strips, Xiangfa Wu, Yuris A. Dzenis, Bradley D. Rinschen Nov 2004

Screw Dislocation Interacting With Interfacial Edge-Cracks In Piezoelectric Bimaterial Strips, Xiangfa Wu, Yuris A. Dzenis, Bradley D. Rinschen

Department of Engineering Mechanics: Faculty Publications

This paper is concerned with the interaction between an interfacial edge-crack and a screw dislocation under out-of-plane mechanical and in-plane electric loading in a piezoelectric bimaterial strip. In addition to a discontinuous electric potential across the slip plane, the dislocation is subjected to a line-force and a line-charge at the core. Under the framework of linear piezoelectricity, the out-of-plane displacement and in-plane electric potentials are constructed in closed-form by means of conformal mapping technique and the known solution for screw dislocation in cracked piezoelectric bimaterial. The intensity factors (IFs) and energy release rate (ERR) are derived explicitly.


Spinning Continuous Fibers For Nanotechnology, Yuris A. Dzenis Jun 2004

Spinning Continuous Fibers For Nanotechnology, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Nanotubes of carbon and other materials are arguably the most fascinating materials playing an important role in nanotechnology today. Their unique mechanical, electronic, and other properties are expected to result in revolutionary new materials and devices. However, these nanomaterials, produced mostly by synthetic bottom-up methods, are discontinuous objects, and this leads to difficulties with their alignment, assembly, and processing into applications. Partly because of this, and despite considerable effort, a viable carbon nanotube–reinforced supernanocomposite is yet to be demonstrated. Advanced continuous fibers produced a revolution in the field of structural materials and composites in the last few decades as a …


Continuum Modeling Of Cell Membranes, Eveline Baesu, R. E. Rudd, J. Belak, M. Mcelfresh Jan 2004

Continuum Modeling Of Cell Membranes, Eveline Baesu, R. E. Rudd, J. Belak, M. Mcelfresh

Department of Engineering Mechanics: Faculty Publications

In this paper, we develop a finite-deformation model for cell membranes with a view toward characterizing the local mechanical response of membranes in atomic force microscope (AFM) experiments. The membrane is modeled as a 2-D fluid continuum endowed with bending resistance. The general theory is used to obtain equations that describe axisymmetric equilibrium states. The membrane is assumed to enclose a fluid medium, which transmits hydrostatic pressure to the membrane, and a point load is applied at the pole to simulate an AFM probe. Both types of loading are associated with a potential and the problem is then cast in …


Screw Dislocation Interacting With Twin Interfacial Edge Cracks Between Two Bonded Dissimilar Piezoelectric Strips, Xiangfa Wu, Yuris A. Dzenis, Tian-You Fan Nov 2003

Screw Dislocation Interacting With Twin Interfacial Edge Cracks Between Two Bonded Dissimilar Piezoelectric Strips, Xiangfa Wu, Yuris A. Dzenis, Tian-You Fan

Department of Engineering Mechanics: Faculty Publications

This paper is concerned with the electroelastic potentials and the fracture parameters of a twin-edge-cracked piezoelectric bimaterial strip with a screw dislocation. By means of conformal mapping technique and the known dislocation solution, the antiplane displacement and inplane electric potentials are obtained in closed-form. The intensity factors and the energy release rate are extracted explicitly. In some limiting cases, the present solutions cover those in the literature.


Method For Performing Accelerated Characterization Of Viscoelastic Constitutive Behavior Of Asphaltic Concrete, Curtis Berthelot, D. H. Allen, Chad Searcy Oct 2003

Method For Performing Accelerated Characterization Of Viscoelastic Constitutive Behavior Of Asphaltic Concrete, Curtis Berthelot, D. H. Allen, Chad Searcy

Department of Engineering Mechanics: Faculty Publications

Constitutive models based in continuum mechanics are formulated for modeling the time dependent mechanical re¬sponse of asphaltic concrete. The model chosen for the initial phase of study is linear viscoelastic, resulting in stress-strain re¬lations that are of the single integral Boltzmann type in time. Experimental equipment and testing protocols are described for obtaining material properties within the viscoelastic framework selected for characterization. A frequency sweep experimental technique is described for obtaining composite properties from short-term tests that can be used to predict long-term, time-depen¬dent material behavior. Mathematical techniques are described for converting experimentally obtained complex compliances to creep compliances and …


Two Semi-Infinite Interfacial Cracks Between Two Bonded Dissimilar Elastic Strips, Xiangfa Wu, Yuris A. Dzenis, Tian-You Fan Sep 2003

Two Semi-Infinite Interfacial Cracks Between Two Bonded Dissimilar Elastic Strips, Xiangfa Wu, Yuris A. Dzenis, Tian-You Fan

Department of Engineering Mechanics: Faculty Publications

The complex stress intensity factor and energy release rate are obtained for two semi-infinite interfacial cracks between two bonded dissimilar elastic strips with equal thickness under inplane deformations. During the procedure, by means of conformal mapping technique, the mixed boundary-value problem is reduced to a standard Riemann–Hilbert problem, which is further solved in closed-form. In some limiting cases, the present explicit solutions can cover the well-known results in the literature.